Ernest W. Brown was born in England and educated at Cambridge University, where he studied under celestial mechanician George H. Darwin. He taught mathematics from 1891 to 1907 at Haverford College and from 1907 to 1932 at Yale University. Starting with refinements of George W. Hill’s work, Brown devoted his career to the theory of the Moon’s motion and constructing accurate lunar tables. His theory took account of “the gravitational action of every particle of matter which can have a sensible effect on the Moon’s motion,” some 1500 terms. He then determined the numerical values of the constants by analyzing 150 years of Greenwich observations, and, with the assistance of Henry B. Hedrick and punched card machines, computed tables accurate to 0.01 arcsec. He showed that some small discrepancies in the apparent motion of the Moon are actually due to fluctuations in the Earth’s rotation rate. He also worked on orbits of Trojan asteroids, a satellite of Jupiter, and trinary star systems.